NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Halley's lunar knowledge.
From: Fred Hebard
Date: 2007 Nov 26, 17:44 -0500
From: Fred Hebard
Date: 2007 Nov 26, 17:44 -0500
On Nov 25, 2007, at 11:20 PM, Michael Daly wrote: > > George Huxtable wrote: >> and for some reason he pointed to an anonymous contemporary review of >> Halley's Southern-stars catalogue. I don't understand its >> relevance, but am >> grateful for that mention, as I had not seen it before. > > You said you hadn't read Phil. Trans.vol. 12, no. 141 (1678), 1032-4. > Well, that's it. An anonymous review. > > >> Are those what Daly appears now to dismiss as "raw data"? > > Of course they are raw data. Halley did not go into his friendly, > neighbourhood navigator's supply shop and buy a printed copy of the > lunar information telling him when a particular star would be occulted > _in_the_future_ by the moon. He had data that specified the position > information on the moon - in the past. That's raw data. He has to > use > it along with a model of lunar motion to produce the information he > needs. > > > Mike Mike, You appear to have missed the point of both George and Frank Reed's post that Halley did not need a model; it could be done empirically knowing that the moon was back in the same spot after 18 years x days later, based upon data collected beforehand. Fred --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to NavList@fer3.com To , send email to NavList-@fer3.com -~----------~----~----~----~------~----~------~--~---